Panels

Panels are web-based applications you can install on your VPS
that aim to make managing a server easier. However, many of the
more advanced panels are targetted towards "resellers" who wish to
divide up their server among a number of clients (ie, provide
shared hosting).

Linux

WebMin is a free panel
with basic functionality that can control Apache, FTP, MySQL, SSH
and some other servers. Its a good choice if you have low memory
(256MB or less) because it has no dependencies - its up to you what
services you control with it. Also worth considering if you are to
be the only user. We have a Webmin
quick-install guide in our Knowledge base.

VirtualMin is a free panel that can
configure web, email, FTP, and databases; it also has some
performance graphs. Its primarily intended for use if you want to
provide multiple people with their own hosting. It requires at
least 512MB of memory and installs a number of components you may
not require like ClamAV and ProFTPd.